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(11) | EP 0 082 519 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Method and apparatus for producing welded joint parts of pipes |
(57) Tensile residual stress in an annular welded joint part (2) joining the ends of unit
pipes (1) is mechanically removed by applying repeated hammering strokes against the
inner surface of the pipes over the entire joint part thereby to cause this part to
undergo locally plastic deformation. The repeated hammering strokes, which have a
peening effect, are applied by several automatically operating hammering devices (21)
mounted radially on a rotary head (18) secured to and unitarily moving with a shaft
(6) which is driveable in rotation about its axis and in translation in its axial
direction. |